Referring to FIG. 1, the human venous system of the leg A comprises the superficial venous system, shown in white, and the deep venous system, shown in black, with perforating veins connecting the two systems. The superficial system includes the long or great saphenous vein B and the small saphenous vein C. The deep venous system includes the anterior and posterior tibial veins D, E, which unite to form the popliteal vein F, which in turn becomes the femoral vein G when joined by the short saphenous vein C. The femoral vein G and the great saphenous vein B join at the sapheno-femoral junction H.
The venous system contains numerous one-way valves for directing antegrade blood flow back to the heart. When an incompetent valve is in the flow path, the valve is unable to close, and retrograde flow of the blood away from the heart cannot be stopped. When a venous valve fails, increased strain and pressure occur within the lower venous sections and overlying tissues, sometimes leading to additional, distal valvular failure. Two venous conditions or symptoms that often result from valve failure are varicose veins and more symptomatic chronic venous insufficiency. Current treatments of venous insufficiency include surgical procedures such as vein stripping, vein-segment transplant, and ligation by ablation.
Vein stripping typically consists of tying off, or ligating, and removing the saphenous vein. Vein segment transplant has been employed in certain organ transplant procedures; however, it is not generally employed in the superficial venous system in humans. Ligation by ablation involves the cauterization or coagulation of vascular lumina using thermal energy applied through a delivery device. Energy introduced into the vein lumen causes the vein wall to shrink in cross-sectional diameter or completely collapse, thereby reducing or completely blocking blood flow through the vein.
An alternative treatment involves placement of an occluding implant in the hollow anatomical structure, such as the great saphenous vein. As an example, the implant can be a fibrous body, optionally textured to impart bulk. The implant causes a partial occlusion of the hollow anatomical structure, followed by a complete or substantially complete occlusion, such as by formation of an organic fibrotic occlusion resulting from the body's natural foreign body healing response.